The Obama team, too, is working to use the attention being paid to Medicare on Twitter to push their own message on the issue: a promoted tweet on the search term "Paul Ryan Medicare," from President Obama's Twitter account, hits the Romney-Ryan ticket.

"Romney-Ryan: The Go Back team with the same top-down economic ideas that crashed our economy," the tweet says.

I've written about this kind of advertising before, but this is another example of how mediums like Google and Twitter are a great place for campaigns to respond, in real time, to what's being talked about in the news.